In recent years, devices utilizing the electroluminescence phenomenon have increased in importance. As such a device, a light emitting element such as an electroluminescence element, in which light-emitting materials are formed to be a light-emitting layer, and a pair of electrodes including an anode and a cathode is attached to the light-emitting layer, and light is emitted by applying voltage thereto, becomes a focus of attention. In this kind of electroluminescence element, a hole and an electron are injected from the anode and the cathode, respectively, by applying voltage between the anode and the cathode, and an energy generated by coupling the injected electron and hole in the light-emitting layer is used to perform light emission. In other words, the electroluminescence element is a device utilizing a phenomenon in which the light-emitting material in the light-emitting layer is excited by the energy produced by the coupling, and light is emitted when an excited state returns to a ground state again.
In a case where the light emitting element such as the electroluminescence element is used as an image display device, since the light-emitting material is capable of self-emitting, the device has characteristics that a speed of response as the image display device is fast and a view angle is wide. Further, due to its structural feature of the electroluminescence element, there is an advantage that the thickness of the image display device may be reduced with ease. Moreover, in a case of an organic electroluminescence element using, for example, an organic substance as the light-emitting material, characteristics are obtained such that light with high color purity is readily obtained depending upon selection of the organic substance, and thereby a wide color gamut is available.
Further, since the light emitting element such as the electroluminescence element is capable of emitting white light, and is an area light source, a use of the electroluminescence element to be incorporated into an illuminating device is suggested.
As an example of the aforementioned light emitting element, Patent Document 1, for example, suggests a cavity-emission electroluminescence device including a dielectric layer interposed between a hole-injecting and electron-injecting electrode layers, in which an internal cavity extends through at least the dielectric layer and one of the electrode layers and includes a hole-injecting electrode region, an electron-injecting electrode region and a dielectric region, and an electroluminescence coating material is applied to the surface of the internal cavity.